1. Field of the Invention
The present invention relates to a waste toner conveying device used in an image forming apparatus of electrophotographic system and an image forming apparatus.
2. Description of the Related Art
Generally, a color image forming apparatus has steps of forming toner images of four colors such as yellow (Y), magenta (M), cyan (C) and black (K) on one photoconductor or a plurality of photoconductors, overlapping the toner images on an intermediate transfer belt, transferring the overlapped toner images on a paper by a paper transfer roller and then fixing the transferred toner images. In such a color image forming apparatus, a cleaning device is provided on each of a photoconductor, an intermediate transfer belt, and a paper transfer roller (referred to as a photoconductor cleaning device, a paper-transfer cleaning device and an intermediate-transfer cleaning device, respectively) so as to remove remaining transferred toner images, toner images which are formed at a non-image area for adjusting image density, or the like. To the paper transfer roller and the intermediate transfer belt, paper powder is attached due to contact with a transfer paper when transferring. Therefore, paper powder is mixed in each of the waste toners in the paper-transfer and intermediate-transfer cleaning devices provided on the paper transfer roller and the intermediate transfer belt. Remaining transferred toner is continuously input on an image area of each of the photoconductor and intermediate-transfer cleaning devices provided on the photoconductor and the intermediate transfer belt. On the other hand, toner is not input on an image area of the paper transfer roller and only small amount of toner of toner images formed on a non-image area for adjusting image density is input. Accordingly, the paper-transfer cleaning device provided on the paper transfer roller has paper powder in waste toner at a mixed ratio higher than the other cleaning devices. That is, a relation of the paper powder mixed ratios between the cleaning devices is generally shown by the following relationship:A>B≧Cwhere A is the mixed ratio of paper powder in the waste toner (referred to as paper-transfer waste toner) in the paper-transfer cleaning device provided on the paper transfer roller, B is the mixed ratio of paper powder in the waste toner (referred to as intermediate-transfer waste toner) in the intermediate-transfer cleaning device provided on the intermediate transfer belt, and C is the mixed ratio of paper powder in the waste toner (referred to as photoconductor waste toner) in the photoconductor cleaning device provided on the photoconductor.
In other words, the paper-transfer waste toner in the paper-transfer cleaning device has a high mixed ratio of paper powder, the photoconductor waste toner in the photoconductor cleaning device has a low mixed ratio of paper powder, and the intermediate-transfer waste toner in the intermediate-transfer cleaning device has a mixed ratio of paper powder, which is lower than the waste toner of the paper transfer roller and equal to or more than the waste toner of the photoconductor. When the paper powder is mixed in the waste toner, flowability of the waste toner is remarkably decreased. Accordingly, a relation of the flowabilities of the waste toners in the cleaning devices is shown by the following relationship:A′<B′≦C′where A′ is the flowability of the waste toner in the paper-transfer cleaning device provided on the paper transfer roller, B′ is the flowability of the waste toner in the intermediate-transfer cleaning device provided on the intermediate transfer belt, and C′ is the flowability of the waste toner in the photoconductor cleaning device provided on the photoconductor.
Accordingly, the flowability of the waste toner of the paper transfer roller is low, the flowability of the waste toner of the photoconductor is high, and the flowability of the waste toner of the intermediate transfer roller is equal to or less than the waste toner of the photoconductor. The waste toners discharged from each cleaning device pass toner conveying paths provided in an image forming apparatus to convey the waste toners to a waste toner tank. The toner conveying paths are laid around components of image forming parts in the image forming apparatus. Accordingly, the toner conveying path is often connected to a delivery part outside of the cleaning device and bent at a substantially-right angle at the delivery part. At the delivery part where the toner conveying path is bent at the substantially-right angle, the waste toner is not smoothly flowed. Under difficult circumstances where a paper having large amount of paper powder is used, an image area is not small, that is, amount of the waste toner is also small and therefore a mixed ratio of paper powder in the waste toner is relatively increased, or temperature in the apparatus is increased due to continuous working of the image forming apparatus, the flowability of the waste toner which may have paper powder is decreased so that the toner is easily clogged at the delivery part. Configurations and operations of representative prior arts will be explained as follows.
FIG. 1 is an explanatory view illustrating a layout of an image forming part of a conventional image forming apparatus, which is used in an embodiment of the present invention. The image forming apparatus includes a photoconductor 1 as an image carrier, a charging device 2, an exposure device 3, a development device 4, a paper transfer roller 5, a resist roller 6, a fixing device 7, a photoconductor cleaning device 100 provided on the photoconductor 1, and a paper-transfer cleaning device 101 provided on the paper transfer roller 5. In the image forming apparatus having such a configuration, charging the photoconductor, exposing the charged photoconductor to form an electrostatic latent image, transferring the electrostatic latent image and cleaning waste toner are continuously performed at each parts as shown in FIG. 1 while the photoconductor 1 rotates, so that an image is formed on a transfer paper 8 fed from the resist roller 6 at an appropriate timing. The image formed on the transfer paper 8 is then fixed by the fixing device 7 and the transfer paper 8 on which the image is fixed is discharged from the image forming apparatus. In the photoconductor cleaning device 100, a waste toner conveying path 110 is provided and waste toner stored on the photoconductor 1 falls on the waste toner conveying path 110. The fallen waste toner is conveyed by rotating a not-illustrated conveying member such as a conveying coil, an auger, or the like, provided in the waste toner conveying path 110 in the photoconductor cleaning device 100 in a horizontal direction.
Similarly, in the paper-transfer cleaning device 101, a waste toner conveying path 112 is provided and waste toner stored on the paper transfer roller 5 falls on the waste toner conveying path 112. The fallen waste toner is conveyed by rotating a not-illustrated conveying member provided in the waste toner conveying path 112 in the paper-transfer cleaning device 101 in a direction perpendicular to a plane represented in FIG. 1. By both of the waste toner conveying paths, the waste toner is conveyed in a vertical direction to a delivery part configured to deliver the waste toner to a forwarding path or combined part where other conveying or forwarding path is combined. The detailed explanation of the waste toner conveying or forwarding paths will be described as follows.
In the above-mentioned configuration, in FIG. 1, only one set of the photoconductor 1 and the paper transfer roller 5, the photoconductor cleaning device 100 and the paper-transfer cleaning device 101 provided around the photoconductor 1 is shown. However, the image forming apparatus may have plural (four) sets thereof respectively corresponding to plural (four) colors such as Y, M, C, Bk as a color image forming apparatus and only one set may be shown by omitting other three sets of these configurations.
FIG. 9 is a schematic view illustrating flowabilities of waste toners and conveying directions for conveying the waste toner in waste toner conveying and forwarding paths in a conventional waste toner conveying device of the image forming apparatus (prior art 1). In FIG. 9, arrows indicate directions where the waste toner is conveyed and patterns in arrows indicate flowabilities of the waste toner, that is, a blanked arrow indicates high flowability, a mesh arrow indicates middle flowability, and filled arrow indicates low flowability (same in the following prior arts 2 to 7). In FIG. 9, reference numbers 210, 211, 212, 213, 214, and 215 indicate paths configured to convey the waste toner, and each path has a conveying member configured to rotate for flowing the waste toner in the directions indicated by the arrows. Reference numbers 220, 221, 222, and 223 indicate delivery parts configured to deliver the waste toner from one path to another path. The path of the waste toner is bent at a substantially-right angle at each delivery part.
Waste toner having relatively-high flowability is stored in the photoconductor cleaning device 100, and waste toner having relatively-low flowability, where paper powder is mixed, is stored in the paper-transfer cleaning device 101. The waste toners are configured to fall in the waste toner conveying paths 210, 212 provided in the cleaning devices 100, 101, respectively.
The waste toner having the relatively-high flowability stored in the photoconductor cleaning device 100 is conveyed from the conveying path 210 to a waste toner storage tank 102 via the delivery part 220, the forwarding path 211, the delivery part 221, and then the forwarding path 213. On the other hand, the waste toner having the relatively-low flowability stored in the paper-transfer cleaning device 101 is conveyed from the conveying path 212 to the waste toner tank 102 via the delivery part 222, the forwarding path 214, the delivery part 223, and then the forwarding path 215.
In such a waste toner conveying device, the delivery parts 220, 221 are not clogged with the waste toner even under the above-mentioned difficult circumstances. However, there is a problem in that the delivery parts 222, 223 may be clogged with the waste toner due to the low flowability of the waste toner passing through the delivery parts 222, 223 under the above-mentioned difficult circumstances.
FIG. 10 is a schematic view illustrating flowabilities of waste toners and conveying directions for conveying the waste toner in waste toner conveying and forwarding paths in another conventional waste toner conveying device of the image forming apparatus (prior art 2). In FIG. 10, reference numbers 310, 311, 312, 313 and 314 indicate paths configured to convey the waste toner, and each path has a conveying member configured to rotate for flowing the waste toner in the directions indicated by the arrows. Reference numbers 320 and 322 indicate delivery parts configured to deliver the waste toner from one path to another path. The path of the waste toner is bent at a substantially-right angle at each delivery part. Reference number 321 indicates a T-shaped combined part where two paths are combined in a T-shaped form, that is, one path is linear and another path is bent at a substantially-right angle.
Waste toner having relatively-high flowability is stored in the photoconductor cleaning device 100, and waste toner having relatively-low flowability, where paper powder is mixed, is stored in the paper-transfer cleaning device 101. The waste toners are configured to fall in the waste toner conveying paths 310, 312 provided in the cleaning devices 100, 101, respectively.
The waste toner having the relatively-high flowability stored in the photoconductor cleaning device 100 is conveyed from the conveying path 310 to a waste toner storage tank 102 via the delivery part 320, the forwarding path 311, the combined part 321, the forwarding path 313, the delivery part 322, and then the forwarding path 314. On the other hand, the waste toner having the relatively-low flowability stored in the paper-transfer cleaning device 101 is conveyed from the conveying path 312 to the waste toner tank 102 via the combined part 321, the forwarding path 313, the delivery part 322, and then the forwarding path 314.
In such a waste toner conveying device, the delivery parts 320, 322 are not clogged with the waste toner even under the above-mentioned difficult circumstances because the waste toner passing therethrough has at least middle flowability. However, there is a problem in that the combined part 321 may be clogged with the waste toner because the waste toner passing one of the two combined paths has flowability lower than that passing the other one of the two combined paths under the above-mentioned difficult circumstances.
FIG. 11 is a schematic view illustrating flowabilities of waste toners and conveying directions for conveying the waste toner in waste toner conveying and forwarding paths in another conventional waste toner conveying device of the image forming apparatus (prior art 3). In FIG. 10, reference numbers 410, 411, 412, 413 and 414 indicate paths configured to convey the waste toner, and each path has a conveying member configured to rotate for flowing the waste toner in the directions indicated by the arrows. Reference numbers 420 and 422 indicate delivery parts configured to deliver the waste toner from one path to another path. The path of the waste toner is bent at a substantially-right angle at each delivery part. Reference number 421 indicates a T-shaped combined part where two paths are combined in a T-shaped form, that is, one path is linear and another path is bent at a substantially-right angle.
Waste toner having relatively-low flowability, where paper powder is mixed, is stored in the paper-transfer cleaning device 101 and waste toner having relatively-high flowability is stored in the photoconductor cleaning device 100. The waste toners are configured to fall in the waste toner conveying paths 412, 410 provided in the cleaning devices 101, 100, respectively.
The waste toner having the relatively-low flowability stored in the paper-transfer cleaning device 101 is conveyed from the conveying path 412 to a waste toner storage tank 102 via the delivery part 420, the forwarding path 411, the combined part 421, the forwarding path 413, the delivery part 422, and then the forwarding path 414. On the other hand, the waste toner having the relatively-high flowability stored in the photoconductor cleaning device 100 is conveyed from the conveying path 410 to the waste toner tank 102 via the combined part 421, the forwarding path 413, the delivery part 422, and then the forwarding path 414.
In such a waste toner conveying device, the delivery part 422 is not clogged with the waste toner even under the above-mentioned difficult circumstances because the waste toner passing therethrough has at least middle flowability. However, there is a problem in that the delivery part 420 may be clogged with the waste toner because of low flowability under the above-mentioned difficult circumstances. Furthermore, there is a problem in that the combined part 421 may be clogged with the waste toner because the waste toner passing one of the two combined paths has flowability lower than that passing the other one of the two combined paths under the above-mentioned difficult circumstances
In an image forming apparatus having a plurality of cleaning devices, a layout where a plurality of waste toner conveying paths are combined with the others to convey the waste toner to the waste toner tank is often used. In the combined part, when the waste toner having relatively-high flowability from one side and the waste toner having relatively-low flowablity from the other side flow to the combined part, the waste toner having high flowability tends to selectively flow and pass through the combined part. Therefore, under the above-mentioned difficult circumstances, the conveying path is easily clogged just before the combined part with the waste toner having low flowability. Accordingly, when the toner clogging occurs, the not-illustrated conveying member provided in the waste toner conveying path is locked and broken. Representative configurations, operations and the like of conventional examples will be explained as follows.
FIG. 3 is an explanatory view illustrating a layout of an image forming part of a conventional image forming apparatus, which is used in another embodiment of the present invention. The image forming apparatus includes a photoconductor 51 as an image carrier, a charging device 52, an exposure device 53, a development device 54, a first transfer roller 55, an intermediate transfer belt 56, a paper transfer roller 57, a resist roller 58, a fixing device 60, a photoconductor cleaning device 500 provided on the photoconductor 51, an intermediate-transfer cleaning device 501 provided on the intermediate transfer belt 56 and a paper-transfer cleaning device 502 provided on the paper transfer roller 57. In the image forming apparatus having such a configuration, charging the photoconductor, exposing the charged photoconductor to form an electrostatic latent image, transferring the electrostatic latent image and cleaning waste toner are continuously performed at each parts as shown in FIG. 3 while the photoconductor 51 and the intermediate transfer belt 56 rotate respectively, so that an image is formed on a transfer paper 61 fed from the resist roller 58 at an appropriate timing. The image formed on the transfer paper 61 is then fixed by the fixing device 60 and the transfer paper 61 on which the image is fixed is discharged from the image forming apparatus. The development device 54 is a so-called revolver-type development device where four development devices 54Bk, 54C, 54M, 54Y are disposed about an axis of rotation and rotated about the axis of rotation so as to develop toner images with the toners included in the development devices on the photoconductor 51.
In the photoconductor cleaning device 500, a waste toner conveying path 510 is provided and waste toner stored on the photoconductor 51 falls on the waste toner conveying path 510. The fallen waste toner is conveyed by rotating a not-illustrated conveying member provided in the waste toner conveying path 510 in the photoconductor cleaning device 500 in a horizontal direction.
Similarly, in the intermediate-transfer cleaning device 501, a waste toner conveying path 512 is provided and waste toner stored on the paper transfer roller 5 falls on the waste toner conveying path 512. The fallen waste toner is conveyed by rotating a not-illustrated conveying member provided in the waste toner conveying path 512 in a horizontal direction.
Furthermore, in the paper-transfer cleaning device 502, a waste toner conveying path 514 is provided and waste toner stored on the paper transfer roller 57 falls on the waste toner conveying path 514. The fallen waste toner is conveyed by rotating a not-illustrated conveying member provided in the waste toner conveying path 514 in a horizontal direction.
By each waste toner conveying path, the waste toner is conveyed in a direction perpendicular to a plane represented in FIG. 3 to a delivery part configured to deliver the waste toner to a forwarding path or combined part where other conveying or forwarding path is combined. The detailed explanation of the waste toner conveying or forwarding paths will be described as follows.
In the above-mentioned configuration, in FIG. 3, only one set of the photoconductor 51 and the charging device, the photoconductor cleaning device and the like around the photoconductor 51 is shown. However, the image forming apparatus may have plural (four) sets thereof respectively corresponding to plural (four) colors such as Y, M, C, Bk as a color image forming apparatus and only one set may be shown by omitting other three sets of these configurations In FIG. 3, reference number 59 indicates a feeding belt of the transfer paper 61.
FIG. 12 is a schematic view illustrating flowabilities of waste toners and conveying directions for conveying the waste toner in waste toner conveying and forwarding paths in a conventional waste toner conveying device of the image forming apparatus (prior art 4). In FIG. 12, arrows indicate directions where the waste toner is conveyed and patterns in arrows indicate flowabilities of the waste toner. In FIG. 12, reference numbers 810, 811, 812, 813, 814, 815, 816 and 817 indicate paths configured to convey the waste toner, and each path has a conveying member configured to rotate for flowing the waste toner in the directions indicated by the arrows. Reference numbers 820, 822, 823, and 824 indicate delivery parts configured to deliver the waste toner from one path to another path. The path of the waste toner is bent at a substantially-right angle at each delivery part. In addition, reference number 821 indicates a T-shaped combined part where two paths are combined in a T-shaped form, that is, one path is linear and another path is bent at a substantially-right angle.
Waste toners having relatively-high flowability are stored in the photoconductor cleaning device 500 and the intermediate-transfer cleaning device 501, respectively. On the other hand, waste toner having relatively-low flowability, where paper powder is mixed, is stored in the paper-transfer cleaning device 502. The waste toners are configured to fall in the waste toner conveying paths 810, 812 and 814 provided in the cleaning devices, respectively.
The waste toner having the relatively-high flowability stored in the photoconductor cleaning device 500 passes through the conveying path 810, turns at a substantially-right angle at the delivery part 820, passes through the forwarding path 811 and then is conveyed to the combined part 821. The waste toner having the relatively-high flowability (slightly less than that stored in the photoconductor cleaning device but relatively-high in the waste toner conveying device of the prior art 4) stored in the intermediate-transfer cleaning device 501 passes through the conveying path 812, turns at a substantially-right angle at the delivery part 821, and then passes through the forwarding path 813 while flowing together with the waste toner discharged from the photoconductor cleaning device 500. At this time, flowability of the mixed waste toners in the forwarding path 813 is maintained high. Then, the mixed waste toners pass through the delivery part 822 and the forwarding path 817, and are finally conveyed to the waste toner tank 503 and stored. On the other hand, the waste toner having relatively-low flowability stored in the paper-transfer cleaning device 502 passes through the conveying path 814, turns at a substantially-right angle at the delivery part 823, and then passes through the forwarding path 815, the delivery part 824 and the forwarding path 816 and is conveyed to the waste toner tank 503.
In such a waste toner conveying device, the delivery parts 820, 822 are not clogged with the waste toner even under the above-mentioned difficult circumstances because of at least middle flowability of the waste toner. The combined part 821 is not clogged with the waste toner even under the above-mentioned difficult circumstances because of high flowability of each of the two conveyed waste toners. However, there is a problem in that the delivery parts 823, 824 may be clogged with the waste toner due to the low flowability of the waste toner passing through the delivery parts 823, 824 under the above-mentioned difficult circumstances.
FIG. 13 is a schematic view illustrating flowabilities of waste toners and conveying directions for conveying the waste toner in waste toner conveying and forwarding paths in a conventional waste toner conveying device of the image forming apparatus (prior art 5). In FIG. 13, reference numbers 910, 911, 912, 913, 914, 915 and 916 indicate paths configured to convey the waste toner, and each path has a conveying member configured to rotate for flowing the waste toner in the directions indicated by the arrows. Reference numbers 920 and 923 indicate delivery parts configured to deliver the waste toner from one path to another path. The path of the waste toner is bent at a substantially-right angle at each delivery part. In addition, each of reference numbers 921, 922 indicates a T-shaped combined part where two paths are combined in a T-shaped form, that is, one path is linear and another path is bent at a substantially-right angle.
Waste toners having relatively-high flowability are stored in the photoconductor cleaning device 500 and the intermediate-transfer cleaning device 501, respectively. On the other hand, waste toner having relatively-low flowability, where paper powder is mixed, is stored in the paper-transfer cleaning device 502. The waste toners are configured to fall in the waste toner conveying paths 910, 912 and 914 provided in the cleaning devices 500, 501 and 502, respectively.
The waste toner having the relatively-high flowability stored in the photoconductor cleaning device 500 passes through the conveying path 910, turns at a substantially-right angle at the delivery part 920, passes through the forwarding path 911 and then is conveyed to the combined part 921. The waste toner having the relatively-high flowability (slightly less than that stored in the photoconductor cleaning device but relatively-high in the waste toner conveying device of the prior art 5) stored in the intermediate-transfer cleaning device 501 passes through the conveying path 912, turns at a substantially-right angle at the delivery part 921, and then passes through the forwarding path 913 while flowing together with the waste toner discharged from the photoconductor cleaning device 500. At this time, flowability of the mixed waste toners in the forwarding path 913 is maintained high. Then, the mixed waste toner is conveyed to the delivery part 922. On the other hand, the waste toner having relatively-low flowability stored in the paper-transfer cleaning device 502 passes through the conveying path 914, turns at a substantially-right angle at the delivery part 922, and then passes through the forwarding path 915, the delivery part 923 and the forwarding path 916 while flowing together with the waste toners discharged from the cleaning devices 500, 501, and is conveyed to the waste toner tank 503.
In such a waste toner conveying device, the delivery parts 920, 923 are not clogged with the waste toner even under the above-mentioned difficult circumstances because of at least middle flowability of the waste toner. The combined part 921 is not clogged with the waste toner even under the above-mentioned difficult circumstances because of high flowability of each of the two conveyed waste toners. However, there is a problem in that the delivery part 922 may be clogged with the waste toner due to the low flowability of one of the waste toners from two sides under the above-mentioned difficult circumstances.
In Japanese Patent Number 3308138, as one of the most close prior art (prior art 6), as shown in FIG. 14, waste toner discharged from an intermediate-transfer cleaning device 501 is conveyed to a conveying path 1010 of a photoconductor cleaning device 500 of a photoconductor via paths 1012, 1011. Reference numbers 1013, 1014 indicate forwarding paths each configured to convey the waste toner from the conveying path 1010 in the photoconductor cleaning device 500 to a waste toner tank 503. Reference numbers 1022, 1023 indicate delivery parts. In Japanese Patent Number 3308138, in order to improve user operability, the waste toner tank is appropriately exchanged while dispensing with needlessness, such as discarding an empty waste toner tank. Although this object is not same as that of the present invention, the configuration, where waste toner discharged from one cleaning device passes through a conveying path in another cleaning device, is similar to that of the present invention. However, in this configuration of the prior art 6, the waste toner having relatively-low flowability discharged from the intermediate-transfer cleaning device passes delivery parts 1021, 1020 which is bent at a substantially-right angle and then is conveyed to the photoconductor cleaning device where the waste toner having relatively-high flowability is stored. The waste toner of the intermediate transfer belt has more paper powder than the waste toner of the photoconductor and therefore the flowability of the waste toner of the intermediate transfer belt is relatively low. Accordingly, it cannot be expected that the two delivery parts 1021, 1020 is prevented from being clogged with the waste toner of the intermediate transfer belt.
FIG. 7 is an explanatory view illustrating a layout of an image forming part of another conventional image forming apparatus, which is used in another embodiment of the present invention. The image forming apparatus includes photoconductors 71Y, 71M, 71C, 71K as image carriers, charging devices 72Y, 72M, 72C, 72K, exposure devices 73Y, 73M, 73C, 73K, development devices 74Y, 74M, 74C, 74K, first transfer rollers 76, 77, 78, 79, an intermediate transfer belt 80, photoconductor cleaning devices 1110Y, 1110M, 1110C, 1110K of the photoconductors 71Y, 71M, 71C, 71K, an intermediate-transfer cleaning device 1130 of the intermediate transfer belt 80, a paper transfer roller 83, a paper-transfer cleaning device 1150 of the paper transfer roller 83, a resist roller 85, a paper feeding belt 86, a fixing device 87, and the like. In the image forming apparatus having such a configuration, charging the photoconductors, exposing the charged photoconductors to form electrostatic latent images, transferring the electrostatic latent images as a primary transfer and cleaning waste toner of the photoconductors are continuously performed at each parts as shown in FIG. 7 while the photoconductors 71Y to 71K and the intermediate transfer belt 80 rotate respectively, so that toner images are formed on the intermediate transfer belt 80 which rotates at a speed substantially equal to that of the photoconductors. The toner images formed on the intermediate transfer belt 80 are then transferred at a time by the paper transfer roller 83 on a paper 90 which is fed by the resist roller 85. Then, the paper where the toner images are transferred is fed by the paper feeding belt 86 and the toner images are fixed by the fixing device 87 on the paper and then, the paper is discharged from the image forming apparatus. In the photoconductor cleaning devices 1110Y to 1110K, waste toner conveying paths 1120Y to 1120K are provided and waste toner stored on each of the photoconductors falls on each waste toner conveying paths 1120Y to 1120K, respectively. The fallen waste toners are conveyed by rotating not-illustrated conveying members such as conveying coils, augers, or the like, provided in the waste toner conveying paths 1120Y to 1120K in the photoconductor cleaning devices 1110Y to 1110K in a direction perpendicular to a plane represented in FIG. 7. In the intermediate-transfer cleaning device 1130, a waste toner conveying path 1140 is provided and waste toner stored on the photoconductors falls on the waste toner conveying path 1140. The fallen waste toner is conveyed by rotating a not-illustrated conveying member such as a conveying coil or an auger provided in the waste toner conveying path 1140 in the intermediate-transfer cleaning device 1130 in a direction perpendicular to a plane represented in FIG. 7. In the paper-transfer cleaning device 1150, a waste toner conveying path 1160 is provided and waste toner stored on the paper transfer roller 83 falls on the waste toner conveying path 1160. The fallen waste toner is conveyed by rotating a not-illustrated conveying member provided in the waste toner conveying path 1160 in the paper-transfer cleaning device 1150 in a direction perpendicular to a plane represented in FIG. 7.
FIG. 15 is a schematic view illustrating flowabilities of waste toners and conveying directions for conveying the waste toner in waste toner conveying and forwarding paths in the conventional waste toner conveying device of the image forming apparatus (prior art 7). In FIG. 15, arrows indicate the conveying direction of the waste toners and patterns (mesh) of the arrows indicate flowabilities of the waste toners in five levels. Reference numbers 1311, 1312, 1313, 1314, 1315, 1316, 1317, 1318, 1344, 1345, 1346, 1347, 1341, and 1342 indicate paths configured to convey the waste toner, and each path has a conveying member such as a conveying coil or an auger configured to rotate for flowing the waste toner in the directions indicated by the arrows. Reference numbers 1321, 1322, 1323, 1324, 1325, and 1326 indicate delivery parts configured to deliver the waste toner from one path to another path. The path of the waste toner is bent at a substantially-right angle at each delivery part. In addition, each of reference numbers 1332, 1333 and 1334 indicates a T-shaped combined part where two paths are combined in a T-shaped form, that is, one path is linear and another path is bent at a substantially-right angle.
Waste toner having relatively-high flowability (level 5) is stored in the photoconductor cleaning device 1110K, waste toner having relatively-middle flowability (level 3) is stored in each of the photoconductor cleaning devices 1110Y to 1110C and the intermediate-transfer cleaning device 1130, and waste toner having relatively-low flowability (level 1) is stored in the paper-transfer cleaning device 1150.
The waste toner having middle flowability (level 3) stored in the photoconductor cleaning device 1110Y passes the conveying path 1341, the delivery part 1323, the forwarding path 1316 and the delivery path 1324 and then is conveyed to the conveying path 1342 in the paper-transfer cleaning device 1150. In the conveying path 1342, the waste toner conveyed from the photoconductor cleaning device 1110Y is mixed with the waste toner having relatively-low flowability (level 1) conveyed from the paper-transfer cleaning device 1150 and then the mixed waste toners having flowability of level 4 is obtained at the delivery part 1325. The mixed waste toners pass the delivery part 1325, are conveyed to the waste toner tank 1350 via the forwarding path 1317, the delivery part 1326, the forwarding path 1318 and then stored in the waste toner tank 1350.
The waste toners stored in the photoconductor cleaning devices 1110M, 1110C, 1110K and the intermediate-transfer cleaning devices 1130 respectively, pass through the paths 1344, 1345, 1346, and 1347 via the delivery parts 1321, 1322 and the combined parts 1332, 1333, and 1334 shown in FIG. 15, and are conveyed to the waste toner tank 1350.
In such a waste toner conveying device of the prior art 7, the delivery parts 1321, 1322, 1323, 1324 and the combined parts 1332, 1333, 1334 are not clogged with the waste toners even under difficult circumstances where it works continuously at a high temperature because of at least middle flowability (level 3) of the waste toners. However, there is a problem in that the delivery part 1325, 1326 may be clogged with the waste toner due to less than middle flowability (level 2 or less) of the waste toner passing through the delivery part 1325, 1326 when the device works continuously at a high temperature.